Powerful explosion rocks optics plant in Moscow region. At least 38 injured as blast wave blows out windows in vicinity.

Update: According to the latest reports (12:55 Moscow time), more than 30 people have been injured due to the explosion. Local authorities say that 38 people have been injured, five of whom are in intensive care. Telegram channel Baza puts that figure at 40. Most of the injuries have reportedly been caused by shrapnel. Authorities say there may be people trapped underneath the rubble.

A powerful explosion in Sergiyev Posad, a city in the Moscow region, left up to 20 people injured, according to various reports.

The blast took place at the Zagorsk optics manufacturing plant, as reported by TASS. The plant is being evacuated.

Posts on the social media show a pillar of thick smoke rising over the city following the explosion. The blast wave reportedly blew out the windows in nearby apartment buildings.

TASS reports that 11 people were injured in the incident. Independent news channels, however, name higher figures. Mash writes about 18, and Shot about 20 casualties.

The cause of the explosion is still unclear. The Telegram news channel 112 claimed that the plant had been attacked by a UAV. (Russian emergency services deny this information.) Later, 112 suggested that the blast took place in a warehouse storing fireworks. This information has not been verified.